Pump embodied as a side channel pump

ABSTRACT

A side channel pump, preferably a vacuum pump, includes a driven rotor ( 16 ) and a fixed stator ( 14 ). The rotor ( 16 ) and the stator ( 14 ) define a pump channel circulating in a peripheral direction. Blades are fixed onto the rotor, protruding into the cross-section of the pump channel. The pump channel also includes a blade-free side channel ( 44 ). The pump channel ( 22 ) containing the side channel ( 44 ) extends in a helical manner around the rotor ( 16 ). The pump channel is advantageously not limited to the length of a winding but can have the length of substantially any number of uninterrupted windings. As a result, a high suction performance and a high compression ratio in the pump can be obtained.

BACKGROUND OF THE INVENTION

The invention relates to a side channel pump for supplying liquid andgaseous fluids as well as mixtures of liquid and gas.

Among other things, side channel pumps are used for generating a vacuum.From EP-A-0 170 175, a side channel vacuum pump is known that includesseveral annularly extending pump channels limited by the rotor and bythe stator each. At the rotor, blades are arranged, protruding into therespective pump channel cross-section. From radially inside, the bladesprotrude only into a portion of the pump channel cross-section so thatthe radial outer portion of the pump channel is free of blades. Theblade-free portion of the pump channel is the side channel.

During rotation of the rotor, the fluid molecules are seized by theblades and accelerated in circumferential direction. Due to thecentrifugal force, the fluid molecules are moved outward into theblade-free side channel. In the side channel, the radially outwarddirected movement is again deflected radially inward in the direction ofthe blades, the fluid molecules being strongly braked again by thefriction at the fixed stator wall. The fluid molecules leave the sidechannel in a radially inward direction and are seized by the bladesagain and accelerated in circumferential direction. Through thiscontinuously repeating process, a circumferentially moving helical fluidwhirl develops in the pump channel.

The fluid inlet and the fluid outlet are formed by a stop wall radiallyprotruding from the stator into the blade-free cross-sectional area ofthe side channel. In the region of the stop wall, the incoming fluidflow passes out of the blade-free cross-sectional area of the pumpchannel to a fluid outlet. The portion of the fluid in the region of theblades at that time is not seized by the stop wall and is thereforeentrained by the blades to the fluid inlet at the rear side of the stopwall.

The compressed fluid entrained to the suction side expands again to thesuction pressure on the suction side and is compressed again. This meansthat, in the region of the blades, the pump channel forms a shortcircuit between the pressure side and the suction side of theannular-like pump channel. The pressure losses caused in this mannerproduce heating and noise. In a vacuum pump, several such annular pumpchannels are connected in series or combined with another molecular pumpstage, with a turbomolecular pump stage, for example, for generatinghigh degrees of compression. Because of their simple mechanicalstructure, ease of maintenance, and reliability, side channel pumps arewell suited for industrial use. Due to the plurality of loss-inflictedfluid inlets and outlets, however, the suction capacity and thecompression ratio are limited.

The present invention contemplates an improved apparatus and method thatovercomes the aforementioned limitations and others.

SUMMARY OF THE INVENTION

One advantage of the invention is improved compression in the sidechannel pump.

In one embodiment of the invention, the pump channel no longer extendslike a screw thread about the rotor, rather than in an annular fashion.In this arrangement, the pump channel can comprise more than onewinding, that is, the channel can include a plurality of windings.Moreover, the maximum pump channel length is not limited to one a singlerotor circumference but, due to the helical arrangement, can be extendedto a multiple of the rotor circumference and is just limited by theaxial rotor length. The pump channel can extend continuously over alength of a plurality of windings without the pump channel beinginterrupted by loss-inflicted fluid inlets and outlets. Therefore, anundisturbed helical fluid flow develops in the pump channel over theentire pump channel length. Thus, a high compression of the pump isrealized. Because of the omission of a plurality of fluid inlets andoutlets, the noise emission is reduced as well.

The stator is configured as a surface area of a body of revolution. Forexample, the stator can be cylindrical, conical or parabolic. Therefore,the stator has a simple structure and can be produced inexpensively. Aneasily maintained side channel pump is realized that has a highcompression and suction capacity, generates a fluid flow of lowpulsation level, occupies a small installation space and is adapted tobe produced easily and inexpensively. Since no oil seals are required, afluid is delivered that is free of contaminations.

According to a preferred embodiment of the invention, the rotorcomprises a channel wall laterally defining the pump channel, extendinghelically about the rotor. In the region of the pump channel, the statoris configured so as to have a smooth surface. Most walls of the pumpchannel are provided at the rotor side, i.e., they are moved in thepumping direction. Therefore, the fluid molecules are braked only at asingle wall of the pump channel, namely at the wall formed by thestator. By this arrangement, the suction capacity of the pump isincreased as well.

According to a preferred embodiment, the pump channel extendscontinuously over approximately the entire rotor length. The fluid inletand outlet are provided at the end faces of the rotor, respectively.This means that a single self-contained compression stage extends over aplurality of windings over the entire length of the rotor. Thefront-face fluid inlet and the front-face fluid outlet are spatiallyseparated from each other; this means that between the compression sideand the suction side, there is no short circuit causing a pressure loss.With a single compression stage, a high compression and suction capacitycan thus be realized.

According to a preferred embodiment, the rotor comprises several channelwalls defining several pump channels parallel to each other. Hence, itis a multiple side channel pump having a correspondingly high suctioncapacity.

Preferably, the cross-sectional area of the blades amounts to betweenone fifth and half of the cross-sectional area of the pump channel.

According to a preferred embodiment, the stator surrounds the rotor.Alternatively or in combination therewith, the rotor can also surroundthe stator. Particularly by the combination of both structural shapes ina single rotor or stator, a very compact pump can be realized.

According to a preferred embodiment, the channel wall is arranged so asto be inclined to a radial line of the rotor, namely inclined in thedirection of discharge. This means that the channel wall does notprotrude vertically from a cylindrical rotor, but is inclined towardsthe pressure side. That channel wall of a pump channel that is the rearone in discharge direction has an obtuse angle of more than 90° withrespect to the fixed stator-side channel wall so that the channel walllocated at the rear acts like a scraper scraping the fluid off thestator channel wall and supporting the formation of the helical fluidwhirl in the pump channel.

According to a preferred embodiment, the blades are arranged so as to beinclined to the radial line of the rotor. This means that the blades donot project vertically from a cylindrical rotor but are inclined in thedirection of the channel towards the pressure side. Due to the bladesbeing inclined forwards to the pressure side, the flow component of thefluid in discharge direction is increased, whereby the fluid pressure issimultaneously increased.

Preferably, the pump channel cross-section is larger at the suction-sideend than at the pressure-side end of the rotor. The fluid increasinglycompressed towards the pressure side is delivered in correspondence withits compression in a pump channel with a decreasing cross-section. Thus,the pump channel length is capable of being considerably lengthened,with the axial rotor length remaining constant. In this way, the rotorlength can be kept relatively short so that a compact structure of thevacuum pump is realized.

According to a preferred embodiment, the pump channel comprises a radialstep. The height of a radial step of the pump channel may be smallerthan half the pump channel height. The stepwise reduction of the pumpchannel radius causes a reduction of the circumferential rotor speed,with the fluid compression increasing. Thereby, the friction lossesbetween the rotor-side channel walls and the stator-side channel wallsare reduced. Due to the limitation of the radial pump channel step tohalf the pump channel to height, the preservation of the helical whirlis ensured when the fluid transitions from one pump channel section intothe next pump channel section. In this way, the pressure losses in theradial step are kept small. In the respective pump channel sections, thepump channel is still arranged helically.

According to a preferred embodiment, the rotor-side pump channel walland the rotor have a conical configuration. Thus, the cross-sectionalarea of the pump channel can be reduced in correspondence with thepressure increase in the pump channel towards the pressure side.Further, the circumferential rotor speed is reduced towards the pressureside by reducing the outer diameter of the rotor. The geometry of thepump channel is adapted to the curve of the fluid pressure. Thus, a verycompact structure and a rotor operation in the stator at a low frictionlevel can be realized.

Preferably, a fluid cooling channel is provided that is arranged betweentwo pump channel sections. In this way, an intermediate cooling of thefluid is effected. The fluid is led out of the pump channel by a scraperprojecting into the pump channel, for example, and cooled in a cooledcooling channel and subsequently supplied to a following pump channelsection again. Due to the intensive cooling of the fluid in an externalcooling channel, the heating of the fluid as well as that of the rotorand the stator is limited. In this way, the compression processapproximates isothermal compression, and the input power is reduced.

According to yet another preferred embodiment, the pump channel isarranged at an end face of the rotor, the pump channel including theside channel extends spirally on the rotor end face. Moreover, the pumpchannel can also be arranged on a rotor in the form of a spiral insteadof in the form of a helix. Thus, it is also possible to realize a pumpchannel with several windings which are not interrupted by fluid inletsand outlets. The pump channel extends in a logarithmic spiral orevolvent. The suction side of the pump channel may be arranged on theoutside or in the center of the rotor or stator.

The aforementioned features referring to a pump with a pump channel onthe outside of a rotor can also be applied, in a similar or analogousmanner, to the pump in which the spiral pump channel is arranged on therotor end face.

Numerous advantages and benefits of the present invention will becomeapparent to those of ordinary skill in the art upon reading thefollowing detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take form in various components and arrangements ofcomponents, and in various process operations and arrangements ofprocess operations. The drawings are only for the purpose ofillustrating preferred embodiments and are not to be construed aslimiting the invention.

FIG. 1 shows a longitudinal cross-sectional view of a first embodimentof a side channel pump with a cylindrical rotor and a cylindricalstator.

FIG. 2 a shows a an enlarged cross-sectional view of the pump channelsof the pump of FIG. 17.

FIG. 2 b shows a cross-sectional top view of one of the pump channels ofthe pump of FIG. 1.

FIG. 3 shows a side view of a portion of the rotor of the pump of FIG.17.

FIG. 4 shows a second embodiment of a side channel pump with severalpump channels arranged behind each other in a step-like manner.

FIG. 5 shows a third embodiment of a pump being a side channel pump witha conical rotor and a conical stator.

FIG. 6 shows a fourth embodiment of a side channel pump with a pumpchannel the cross-section of which reduces towards the pressure side.

FIG. 7 shows a fifth embodiment of a side channel pump with ameander-like arrangement of several pump channels.

FIG. 8 shows a top view of a sixth embodiment of a side channel pump,with a spiral pump channel arranged on the rotor side.

FIG. 9 shows a longitudinal cross-sectional view of the vacuum pump ofFIG. 8.

FIG. 10 shows a cross-sectional view of a seventh embodiment of a sidechannel pump, which has a pump channel arranged on the outercircumference of the rotor and an annexed pump channel arranged on therotor end face.

FIG. 11 shows a cross-sectional view of an eighth embodiment of a a sidechannel pump, which has a fluid cooling channel.

FIG. 12 shows a cross-sectional view taken along the sectional lineXII—XII of the pump of FIG. 11.

FIG. 13 shows a cross-sectional view of a ninth embodiment of a sidechannel pump, which has a fluid cooling channel.

FIG. 14 shows a cross-sectional view taken along the sectional lineXIV—XIV of the pump of FIG. 13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, a first embodiment of a pump 10 which is a side channel pump,for delivering a fluid, and preferably for delivering a gas, isillustrated. The pump 10 serves to produce a vacuum on a suction side 11and to compress the fluid into medium vacuum or rough vacuum on apressure side 13.

The side channel vacuum pump 10 is substantially formed by a stator 14forming a fixed housing 12 and a driven rotor 16 in the stator housing12. The rotor 16 is driven by an electric motor (not shown) by which therotor 16 can be rotated at up to 80,000 revolutions/minute. The rotor 16and the stator housing 12 are preferably made of metal, but may also bemade of ceramics, be made of plastics or of a material coated withplastics. The operation of the vacuum pump 10 is preferablylubricant-free so that a contamination of the pumped fluid is avoided.

From the suction side 11 of the vacuum pump 10, the fluid flows througha fluid inlet 48 into the stator housing 12 at the one end face of therotor 16 and flows through a fluid outlet 50 out of the stator housing12 towards the pressure side 13 at the other end face of the rotor 16 ina compressed manner.

The rotor 16 includes an integral rotor body 18 with a shaft 19 and has,disposed at its outer circumference, a single channel wall 20 projectingradially outward, extending over the axial length of the rotor 16 in theform of a helical line with a constant gradient. The helical threadformed in this way is a single-flight thread. Over the entire rotorlength, the channel wall 20 defines therebetween a single pump channel22 extending helically around the rotor circumference.

With continuing reference to FIG. 1 and with further reference to FIG. 2a, in cross-section, a channel bottom 25 formed by the rotor body 18 hasan approximately circular configuration. On the outside or stator side,the pump channel 22 is defined by a cylindrical housing wall 24 of thehousing 12. An inside 26 of the housing wall 24 is preferably smooth.The pump channel 22 extends in a single winding over the entire lengthof the rotor 16.

As illustrated in FIG. 2 a, the channel wall 20 is inclined to a radialline 30 of the rotor 16 at an angle 28 of approximately 15°. The channelwall 20 is inclined such that it is axially bent forward towards thepressure side 13. A pressure-side side 32 of the channel wall 20 thatforms the suction-side wall of the pump channel 22 assumes an obtuseangle with respect to the stator-side inside 26 of the housing wall 24.A pressure-side front edge 34 of the channel wall acts like a scraperwith respect to the inside 26 of the housing wall 24 and thus peelsfluid off the housing inside 26.

In the pressure-side and rotor-side quarter of the pump channelcross-section, a plurality of plate-like blades 38 is arranged at anequal mutual distance. The blades 38 shaped like segments of a circleassume about between a fifth and a half of the cross-sectional area ofthe pump channel, but may also be larger. The blades 38 are arranged inthe region of the suction-side and rotor-side quarter of the channelcross-section. As illustrated in FIG. 2 b, each blade 38 stands at aboutright angles to the channel wall 20 and at an angle 40 of 10°–20° to aradial line 42 of the rotor body 18. Due to the forward inclination ofthe blade 38 in rotational direction or to the pressure side to thefore, the pressure generated in the fluid is increased in comparisonwith blades without inclination. The blades 38 bent forward inrotational direction effect an increased flow component that is directlyproportional to the increase in pressure.

The blade-free stator-side half of the pump channel 22 forms a sidechannel 44 of the pump channel 22. The side channel 44 of the pumpchannel 22 is the outside and blade-free portion of the pump channel 22.

A gap 56 between the channel wall 20 and the inside 26 of the housingwall 24 is sufficiently small so that the backflow caused by thepressure difference between neighboring pump channel passages issubstantially smaller than the pressure difference built up in awinding. The flow resistance of the gap 56 is large, such that it is anobstacle to a considerable fluid backflow in the direction of thesuction side 11. The flow resistance in the gap 56 can be changed byusing a thicker a channel wall 20 and thus a corresponding axiallengthening of the gap 56.

The fluid flows through the fluid inlet 48 into the stator housing 12and is accelerated by the channel wall 20, the channel bottom 25, andthe blades 38 and thus, is tangentially compressed in thecircumferential direction into the circumferential pump channel 22 andsimultaneously delivered axially towards the fluid outlet. In the closedhelical pump channel 22, the fluid or the fluid molecules are moved on ahelical line within the pump channel 22.

As illustrated particularly in FIGS. 2 a and 3, the fluid is acceleratedin circumferential direction of the rotor by the blade 38. Because ofthe acceleration, the centrifugal force acting upon the fluid isincreased so that the fluid flows radially outward into the side channel44. Finally, the fluid abuts against the fixed inside 26 of the statorhousing wall 24 and is braked and reflected radially inward. During thedeceleration at the inside of the stator housing wall 24, fluid flow 54mixes with fluid particles from other channel sections, which havealready been braked at the stator housing wall 24. In the radial innerportion of the pump channel 22 or in the region of the blade 38, thepressure is lower than in the radial outer portion of the pump channel22, i.e., in the side channel 44. A force from the side channel 44 actsradially inward upon the fluid. Further, the braked fluid is peeled offthe inside 26 of the stator wall by the channel wall front edge 34 andthus moved axially towards the fluid outlet 50 by the channel wall 20.From the side channel 44, the fluid flows along the suction-side channelwall side 32 of the channel wall 20 to the channel bottom 25 in whichthe fluid is again deflected radially outward by approximately 180°. Indoing so, it is seized by the blade 38 and accelerated in thecircumferential direction again. This process is repeated until the thuscompressed fluid reaches the outlet-side axial end of the rotor 16 andflows out of the fluid outlet 50 there. In the fluid pump channel 22, ahelical fluid flow 54 is thus generated in the course of which the fluidis increasingly compressed. By means of the described pump, gaseousfluids can be compressed from ultrahigh vacuum to approximatelyatmospheric pressure by a single compression stage.

The present vacuum pump 10 can be realized with a pump channel 22 ofsubstantially any length so that very high compression capacities areachievable. Owing to the continuous fluid compression, loss-inflictedtransitions between different compressor stages are avoided. Thesystem-determined short circuit between the pressure side and thesuction side that exists with conventional side channel compressors thathave annular pump channels is eliminated in the screw thread-like pumpchannel arrangement. Apart from the inside 26 of the stator housing wall24, all walls of a pump channel 22 are configured so as to be rotating,i.e., to compress the fluid. Thereby, the compression capacity of thepresent vacuum pump is increased as well. The flow of the deliveredfluid has a low pulsation level. Due to the few movable parts and thesimple structure, the present vacuum pump can be manufacturedinexpensively and requires only a small extent of maintenance.

In FIG. 4, a second embodiment of a double-lead side channel pump 70 isillustrated, where four steps 72, 73, 74, 75 with pump channels 80–83,80′–83′ of different diameters are provided. Each step 72–75 comprisestwo parallel pump channels 80, 80′; 81, 81′; 82, 82′; 83, 83′, by whichthe suction capacity of the pump 70 is doubled in comparison withsingle-lead pumps. A rotor 86 as well as the a stator housing wall 88are configured so as to be stepped such that the radius of the pumpchannels 80–83 respectively decreases to the pressure side 13 from stepto step, whereas the cross-sectional area of the pump channels 80 B 83,80′–83′ respectively remains the same. The height of each radial step90, 91, 92 amounts to about one third of the radial height of a pumpchannel 80–83, 80′–83′. By limiting the height of the radial step tohalf of the radial pump channel height at maximum, the screw thread-likecourse of the pump channel is largely preserved in the region of theradial steps 90–92 as well. In this way, it is ensured that the helicalfluid flow is substantially undisturbed. Moreover, a considerablepressure loss in the region of the radial steps 90–92 is avoided. Owingto the reduction of the pump channel radius towards the pressure side13, the friction losses between the rotor 86 and the stator housing wall88 are reduced.

In FIG. 5, a third embodiment of a side channel pump 100 is illustratedwhere a rotor 102 as well as a housing wall inside 104 of a stator 106are configured so as to conically taper from the suction side 11 to thepressure side 13. The rotor 102 comprises two pump channels 110 and 111arranged next to each other on the rotor outside in a helical manner.The radial height of the two parallel pump channels 110, 111 is constantover the entire length of the pump channels 110, 111. By the taperingthe rotor 102 and the stator 106 towards the pressure side, frictionbetween rotor 102 and stator 106 is reduced.

In a fourth embodiment of a side channel pump 120 illustrated in FIG. 6,an inside 122 of a stator housing wall 124 has a cylindricalconfiguration. An envelope formed by a rotor 125, which envelope isdefined by outer ends of the channel walls 126, is cylindrical as well.The radial height as well as the axial width of the pump channels 128,128′ continuously decrease from the suction side 11 towards the pressureside 13 so that the slope of the pump channels 128, 128′ decreasestowards the pressure side. Due to the continuous reduction of the pumpchannel cross-section towards the pressure side 13, the pump channellength can be considerably extended, with the axial rotor lengthremaining constant, to enable a more compact design. The reduction ofthe pump channel cross-section towards the pressure side 13 is effectedapproximately analogously to the increase in pressure of the fluid inthe two pump channels 128, 128′. Thus, it is taken into considerationthat the fluid needs less and less space due to the continuouscompression in the pump channels 128, 128′ towards the pressure side 13.

In a fifth embodiment of a pump 140 illustrated in FIG. 7, three pumpchannel ducts 142, 144, 146 are arranged in a meander-like manner and soas to be nested into each other. Thus, the axial length of rotor 148 canbe considerably reduced. In the central pump channel duct 144, wings 150are arranged in the pressure-side and radially inner quarter of the pumpchannel cross-section. Thereby, a helical fluid flow is also generatedin the pump channel 152 of the central pump channel duct 144.

In FIGS. 8 and 9, a sixth embodiment of a pump 170 being side channelpump is illustrated where a pump channel 172 is arranged spirally on anend face of a rotor 174 in a cross-sectional plane of the rotor 174. Thepump channel 172 is radially defined by a channel wall 176 arrangedspirally on rotor body 178, extending over five windings. The channelwall 176 and the pump channel 172 preferably follow a logarithmicspiral. In the illustrated pump 170, a fluid inlet 180 at the suctionside 11 is located at the outer circumference of the rotor 174, and afluid outlet 182 at the pressure side 13 is located in the center of therotor 174. In the pump channel 172, blades 184 in the form of a segmentof a circle of 90° are arranged at the inner channel wall side. The pumpchannel 172 defined by the channel wall 176 and the rotor body 178 isaxially defined by a substantially disk-shaped stator housing 171. Thecompression of the fluid in the pump channel 172 is effected in the samemanner as in the afore-described side channel pumps of FIGS. 1–7.

In a seventh embodiment of a side channel pump 200 illustrated in FIG.10, two helical pump channels 204, 204′ are combined with a spiral pumpchannel 206 annexed thereto on a single rotor 202.

In FIGS. 11–14, two exemplary arrangements for providing fluid coolingare illustrated. In each exemplary arrangement, fluid is led out of therespective pump channel, cooled in a cooling channel and finallysupplied to the pump channel again.

A first embodiment incorporating fluid cooling in a side channel pump220 is illustrated in FIGS. 11 and 12. The pump 220 includes twoparallel pump channels 222, 222′. A fixed strip-shaped scraper 224disposed on a cylindrical stator wall 232 protrudes radially into thetwo parallel pump channels 222, 222′. The scraper 224 has an axiallength approximately corresponding to an axial width of a channel andapproximately protrudes to half the radial height of the pump channels222, 222′ to blades 226 into the pump channel 222. In the region of thescraper 224, a channel wall 228 is limited to the radial height of theblades 226 so that it does not collide with the scraper 224. By thescraper 224, about half of the delivered fluid is led out of the pumpchannels 222, 222′ and led into a cooling channel 230 of a coolingdevice 223. The cooling channel 230 extends about the cylindrical statorwall 232 and is, in turn, surrounded by a cooling agent channel 234. Inthe cooling agent channel 234, a cooling agent flows by which thecooling channel 230 and the fluid flowing therein are cooled. Thecooling channel 230 and the cooling agent channel 234 extend annularlyabout the stator housing wall 232. At the rear side of the scraper 224,the cooled fluid coming from the cooling channel 230 flows into pumpchannels 225, 225′ again. By the cooling device 223, about half of thefluid from the pump channels 222, 222′ is led into the cooling channel230. The other half of the fluid in the region of the blades 226 passesthe scraper 224 and thus the cooling device 223 in a non-cooled manner.While only about half of the fluid is cooled, advantageously the helicalfluid flow in the pump channels 222, 222′, 225, 225′ is onlyinsignificantly disturbed.

In a second embodiment of a side channel pump 240 illustrated in FIGS.13 and 14 that incorporates fluid cooling, a scraper 242 of a coolingdevice 244 radially protrudes beyond the complete radial height of pumpchannels 248, 248′ into a rotor 246. The scraper 242 protrudes into acircumferential annular groove 243 of the rotor 246. Thus, the entirefluid flow from the pump channels 248, 248′ is branched off into acooling channel 250 and cooled there. The cooling channel 250, in turn,is surrounded by a cooling agent channel 252. In order to reducepulsations of the fluid flow, a two-part guide ring 254 ₁, 254 ₂protrudes into the annular groove 243. The guide ring 254 ₁, 254 ₂consists of two half rings 254 ₁, 254 ₂ and is configured so as toextend helically in the same direction as channel walls 256. In thisarrangement, the fluid flow can gradually flow out of the pump channels248, 248′ before impinging onto the scraper 242, before it is deflectedinto the cooling channel 250 by the scraper 242. After the fluid haspassed the cooling channel 250, it is supplied to pump channels 249,249′ again along the guide ring 254 ₂. Thus, the entire fluid flow isled out of the pump channels 248, 248′, cooled and introduced into thefollowing pump channels 249, 249′ again, without the occurrence ofstrong pulsations. Thus, a fluid intermediate cooling can be realizedthat causes only minor pressure losses.

In addition or as an alternative to the afore-described fluid cooling,the stator housing can be cooled by a cooling device. To this end, thestator housing can be surrounded, over its entire circumference and itsentire length, by one or several cooling channels in which a coolingliquid, a cooling gas or another cooling agent flows around the statorhousing.

Through the fluid cooling, the fluid compression approaches anisothermal compression, whereby, in turn, the required rotor power isreduced.

The invention has been described with reference to the preferredembodiments. Obviously, modifications and alterations will occur toothers upon reading and understanding the preceding detaileddescription. It is intended that the invention be construed as includingall such modifications and alterations insofar as they come within thescope of the appended claims or the equivalents thereof.

1. A pump being a side channel pump, comprising: an inlet through whichfluid is received; a driven rotor; a stator, a helical pump channelconfigured in the rotor and defined by a radially outwardly protrudingchannel wall extending helically around the rotor, the pump channelbeing further defined by the stator; blades fixed to the rotor andprotruding into a portion of the pump channel; a blade-free side channelportion forming a helical side channel defined in the pump channel; and,an outlet, fluid received through the inlet being pumped as the rotorrotates through the outlet.
 2. The pump of claim 1, wherein the pumpchannel has more than one winding.
 3. The pump of claim 1, wherein thepump channel continuously extends over substantially an entire rotorlength, and the fluid inlet and the fluid outlet are defined at an endface of the rotor.
 4. The pump of claim 1, wherein the rotor includes: aplurality of channel walls extending from the rotor that define at leasttwo pump channels arranged parallel to each other.
 5. The pump of claim1, wherein a surface area of each blade has a cross-sectional area thatis between one-fifth and one-half of a cross-sectional area of the pumpchannel.
 6. The pump of claim 1, wherein the stator surrounds the rotor.7. The pump of claim 1, wherein the rotor surrounds the stator.
 8. Thepump of claim 1, wherein the channel wall is inclined to a radial lineof the rotor.
 9. The pump of claim 1, wherein each of the blades isinclined to a radial line of the rotor.
 10. The pump of claim 1, whereinthe pump channel has a cross-section that is larger at a suction sidethan at a pressure side of the pump channel.
 11. The pump of claim 10,wherein the pump channel includes at least one radial step.
 12. The pumpof claim 11, wherein a height of the at least one radial step is smallerthan one-half of a radial height of the pump channel.
 13. The pump ofclaim 10, wherein the stator has a conical configuration.
 14. The pumpof claim 1, wherein the helical pump channel includes two helical pumpchannel sections, the pump further including: a cooling channel arrangedbetween the two pump channel sections.
 15. A side channel pumpcomprising: a rotor with a pump channel extending helically along and aplurality of revolutions around the rotor; a stator having a smoothsurface facing the helical pump channel; blades fixed to the rotor andprotruding into the pump channel; and a blade-free side channel portionforming a helical side channel defined in the pump channel, relativerotation of the rotor and the stator pumping a fluid from a suction sideof the pump channel disposed in a fluid communication with an inlet to apressure side of the pump channel in fluid communication with an outlet.16. A pump including: a stator; a rotor that includes a channel wallprotruding from a surface of the rotor, the channel wall including atleast two helical or spiral channel wall turns that cooperate with asurface of the stator to define a helical or spiral pump channel thatextends from a fluid inlet to a fluid outlet; and a plurality of bladessecured to the rotor and extending into the pump channel, the bladesoccupying a limited portion of a cross-sectional area of the pumpchannel, the cross-sectional area of the pump channel further includinga pump channel portion into which the blades do not extend forming ahelical or spiral side channel.
 17. The pump as set forth in claim 16,wherein: the spiral pump channel has a logarithmic spiral shape.